Portable exercise system



FIG. 1 is a perspective view of portable exercise system, showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a front elevational view, the rear elevational view being substantially a mirror image thereof;

FIG. 4 is a right side elevational view, the left side elevational view being substantially a mirror image thereof; and,

FIG. 5 is a bottom plan view thereof. 

The ornamental design for a portable exercise system, as shown and described herein. 